According to Japanese Patent Application Laid-Open (JP-A) No. 2014-006123, by combining a radar and an image sensor, candidates for a target object included in radar data and image sensor data can be evaluated to determine whether or not they are for a same target object. Information of the target object, such as a position and an orientation of the target object, can be estimated when the candidates are for the same target object. Japanese Patent Application Laid-Open (JP-A) No. 2014-006123 discloses a technique of determining whether a reaction of the radar exists in a lateral direction of a threshold from a position of a target object obtained from the image sensor data. The determination may also be based on a comparison of the orientation (and a comparison of the relative speed). Japanese Patent Application Laid-Open (JP-A) No. 2014-006123 also discloses the estimation of the target object information, through a technique of selecting one of the target object information of the radar data and that of the image sensor data, and a technique of integrating different target object information by a weighted sum.